I've found some regional icons on the web and put them up. If I got the wrong flag please let me know and this clueless American will change it.
Not all the icons are up yet. I'm going through and adding icons to each forum (there's a quite a few) as time permits.

I don't particularly like seeing a Spain flag there, but I admit the icons in general look really cool. I won't say I'd like to see the flag of Argentina (at least not until we beat Germany in the World Cup).

You can leave a Spain flag, not a big deal. Might I suggest a different file though? The current Spain flag looks a bit weird. The one at the website suggested by @smed79 looks better. May need some editing though, I see white space around it (Spain-Flag.png). If it was up to me though, I would go for one without the coat of arms. The vast majority of the websites I have seen that use language icons do not put a flag of Spain with the coat of arms. Something like this would be awesome, in my humble opinion: pngimg.com/download/14588 (you will need to resize it, I can help with that if you want me to).